Rotary hand tool

ABSTRACT

A screw-driver or like hand tool with functions in similar fashion to a ratchet screw-driver. The shank is coupled to the handle by a mechanism comprising a housing fitted to the handle, a bore in the housing which is non-cylindrical to define three channels spaced circumferentially of the shank and having outwardly converging side walls and three rollers in rolling contact with the handle end of the shank and disposed one within each end of the channels. The rollers can be positioned so that on rotation of the handle in one direction they are forced inwardly against the shank by virtue of their engagement with the channels to couple the handle and the shank, whereas on reverse rotation of the handle the rollers are free to roll on the shank. The rollers can alternatively be positioned for reverse operation of the screw-driver.

United States Patent Plaw 1 ROTARY HAND TOOL [75] Inventor: GraemeRaymond Plaw,

Nunawading. Australia [73] Assignee: The Stanley Works, New BritainConn.

[22] Filed: May 6, 1974 [21 Appl. No.: 466,970

Related US. Application Data 3.586.143 6/1971 Hutchinson 192/44 PrimaryE.\'aminerAI Lawrence Smith Assistant E.\'aminerJames G. Smith Attorney,Agent, or FirmPrutzman. Hayes, Kalb & Chilton [57 1 ABSTRACT Ascrew-driver or like hand tool with functions in similar fashion to aratchet screw-driver. The shank is coupled to the handle by a mechanismcomprising a housing fitted to the handle, a bore in the housing whichis non-cylindrical to define three channels spaced circumfercntially ofthe shank and having outwardly converging side walls and three rollersin rolling contact with the handle end of the shank and disposed onewithin each end of the channels. The rollers can be positioned so thaton rotation of the handle in one direction they are forced inwardlyagainst the shank by virtue of their engagement with the channels tocouple the handle and the shank. whereas on reverse rotation of thehandle the rollers are free to roll on the shank. The rollers canalternatively be positioned for reverse operation of the screw-driver.

4 Claims, 7 Drawing Figures US. Patent Sept. 30,1975 3,908,487

W67 P; H a? 2 a w y W F/Qi Z97 7 f? I 773 ROTARY HAND TOOL This is acontinuation of application Ser. No.

286,342, filed Sept. 5, 1972, now abandoned.

BACKGROUND OF THE INVENTION- 1. Field .of the Invention This inventionrelates to rotary hand tools and has particular but not exclusiveapplication to screw drivers.

2. Description of Prior Art One very common form of screw driver is theratchet screw driver in which the shank of the driver is coupled to thehandle via a ratchet mechanism which can be set so that when the handleis rotated in one direction it will drive the shank but if rotated inthe reverse direction it will rotate freely on the shank. The ratchetmechanism can alternatively be set so that the handle will drive theshank when rotated in the reverse direction and will rotate freely inthe forward direction. The present invention provides an alternativemechanism which provides these functions but which can be more robustand reliable in operation than a conventional ratchet mechanism. Themechanism of the present invention is also relatively silent inoperation.

SUMMARY OF THE INVENTION According to the invention there is provided arotary hand tool comprising a handle, a shank, and a coupling mechanismto couple the handle to the shank, wherein there is associated with thehandle a pair of wall portions which converge in a direction away fromthe axis of the shank and wherein the coupling mechanism comprises arolling element in rolling contact with the handle'end of the shank andlocated between said wall portions, and rolling element positioningmeans conditionable alternatively to position the rolling elementagainst one or other of the wall portions, such that when the roller isagainst one of said wall portions rotation of the handle in onedirection causes said one wall portion to bear against the rollingelement and force it inwardly against the shank to provide a couplingaction between the handle and the shank whereas on reverse rotation ofthe handle the rolling element is free to roll on the shank, and whenthe rolling element is against the other wall portion rotation of thehandle in the reverse direction causes that other wall portion to bearagainst the rolling element to force it inwardly against the shank toprovide a coupling action between the handle and shank whereas onrotation of the handle in said one direction the rolling element is freeto roll on the shank.

Preferably, said rolling element is an elongate roller and said wallportions define a channel extending longitudinally of the shank.

More particularly. it is preferred that said channel is one of aplurality of channels associated with the handle and spacedcircumferentially around the shank and said roller is one of a likenumber of rollers disposed one to each of the channels. The rollingelement positioning means may then comprise a roller positioning memberholding the rollers in circumferentially spaced relationship androtatable about the handle end of the shank, and detent means to holdthe roller positioning member alternatively in one of two rotationalpositions relative to the handle, each roller being held against oneside wall portion of the respective channel when the roller holdermember is in one of its rotational positions and against the otherchannel side wall portion when the roller holder member is in the otherof its rotational positions.

BRIEF DESCRIPTION OF DRAWINGS In order that the invention may be morefully explained, a preferred form of screw driver will now be describedin some detail with reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal cross-section through the screw driver;

FIG. 2 is a cross-section on the line 2-2 in FIG. 1;

FIGS. 3 and 4 are both cross-sections on the line 3-3 in FIG. 1 showinghow the handle of the screwdriver can drive the stem in one directionbut will rotate freely in the reverse direction.

FIG. 5 is a further cross-section corresponding to that of FIG. 2 butshows a roller cage member of the screw driver moved relatively to thehandle to reverse the drive and free rotation directions;

FIG. 6 is a further cross-section corresponding to that of FIGS. 3 and 4but is taken with the screw driver in the same condition as illustratedin FIG. 5; and

FIG. 7 is a broken elevation of an alternative type of shank which couldbe fitted to the screw driver.

DESCRIPTION OF PREFERRED EMBODIMENT The illustrated screw drivercomprises a handle assembly including a handle member 6, a shank 7, anda mechanism 8 for coupling those two parts together. Handle member 6,which is formed to a pistol grip shape, may be moulded in a celluloseacetate or some other plastics material. Shank 7 is in the form ofacylindrical metal rod having a groove 9 adjacent one end to receive aretaining clip 11 and it is formed at its other end with a blade 12.

Mechanism 8 has a housing 14 which fits snugly into a stepped bore inthe handle member 6 and is permanently coupled to the handle member.Housing 14, which may conveniently be die cast in zinc, has anoncylindrical central bore into which a correspondingly formed mildsteel liner 16 is pressed. The thus lined part of the bore departs fromcylindrical shape such that three longitudinally extending channels areformed at equal intervals around its circumference. More particularly,the inner peripheral surface of the lined bore departs outwardly from acylindrical surface at three positions around its circumference todefine the channels 17, which have outwardly converging side wallportions 17A, 178. Three rollers 18 are disposed within the lined bodybore. These rollers make rolling contact with the inner end of shank 7and are held spaced around the shank by a roller positioning member 19such that one roller engages each of the internal lobes 17 of the linedbore in the body 14.

Roller positioning member 19 comprises a relatively solid outer part 21and a relatively thin-walled tubular inner part 22 in which slots 23 areformed to receive the rollers 18 so that part 22 serves as a rollercage. The extreme outer part of the roller positioning member has aflange 24 which forms an end capping to the handle 6. As will shortly beexplained, the coupling mechanism is set by rotation of the roller cagerelative to the handle and the outer periphery of the flange 24 may beserrated or knurled so that it can be firmly gripped.

In the plane on which the cross-section of FIG. 2 is taken roller cageportion 21 has two generally oppositely disposed circumferential slots26, 27. Slot 26 receives the inner end of a retaining pin 28 whichextends through a hole in body 14 and is held in position by acircumferential retaining spring 29 fitted around the outer end of thebody 14. Retainer pin 28 locates roller cage 19 with respect to body 14in the axial direction but the cage and body can be rotated relative toone another through about 65". During such relative rotation pin 28 willtraverse the length of slot 26 and at the same time a detent ball 31disposed in a hole 32 in body 14 will traverse the opposite groove 27.The root of groove 27 is raised or humped at 33 between its ends so thatin passing from one endof its groove to the other the ball must forcethe retaining spring 29 outwardly in order to traverse the hump 33. Thusball 31 and groove 27 provide a detent action whereby the cage member 19will be held in position at either of its extremes of rotation relativeto the body 14.

When the roller positioning member 19 is in the rotational positionshown in FIGS. 2, 3 and 4 (i.e. rotated anticlockwise relative to thehandle and body 14 when seen in the direction of those views) therollers 18 are disposed against the channel wall portions 17A whichextend back in the anti-clockwise direction from the apices of theinternal lobes.

If the handle 6 and body 14 are then rotated in the clockwise directionas indicated by arrow 34 in FIG. 3, channel wall portions 17A bearagainst rollers 18 and force them inwardly against the inner end ofshank 7. The inward forces on rollers 18 are quite sufficient to causethe rollers to grip shank 7 and to drive it with the handle 6 and body14. If, however, the handle is rotated in the reverse directionindicated by the broken arrow 36 in FIG. 4 the body line 17 does notbear against the rollers 18 which therefore are not forced inwardly andsimply roll on the shank 7 so that the handle will rotate freely aboutthe shank. Thus the screw-driver can be used to drive a screw in exactlythe same fashion as a conventional ratchet screw driver but it will besubstantially silent in operation.

By rotating the roller cage member 19 through 65 relative to the handle6 and body 14 in the clockwise direction the detent ball 31 is moved tothe other end of the detent slot 37 as shown in FIG. 5, and the rollers18 are displaced across the three channels 17 to engage wall portions17B which extend from the apices in the clockwise direction as shown inFIG. 6. Theoperation of the mechanism will'then be reversed in thatrotation of the handle in the anti-clockwise direction will causechannel wall portions 17B to bear against the rollers and cause them togrip the shank 7 whereas on clockwise rotation the handle will rotatefreely about the shank.

The rollers are conveniently formed from hardened steel rod and theliner 16 may be formed of case hardened mild steel tubing to provide ahard wearing surface. Roller positioning member 19 may be moulded from aplastics material. Nylon is particularly suitable since it is tough andwill slide easily over adjacent surfaces of other parts.

FIG. 7 illustrates an alternative form of shank 41 which could be fittedto the screw driver in place of the shank 7. It is similar to shank 7,having a groove 42 adjacent one end to receive the retaining clip 11 butit has a different type of blade tip 43.

It has been found that the inward forces on the roller generated by thewedging action on the channel wall portions are quite sufficient toprovide a very strong coupling between the handle and the shank and theillustrated screw driver is very positive in operation. It is also ofvery robust construction and has fewer parts than a conventional ratchetmechanism. Conventional ratchet mechanisms comprise pinions and pawlsand their effective life is often determined by pinion failure. It isanticipated that the illustrated construction will provide much longerservice. This construction has. however. been advanced by way of exampleonly and many modifications could be made to it. For example. it is notessential that the coupling mechanism have three channels and respectiverollers. The number of channels and rollers could readily be increasedand it would also be possible to devise a construction with as little asone channel and roller set. It would also be feasible to substituteballs for the rollers and in this case the channels might be replaced byrecesses of generally hemispherical or other convenient shape.

The form of the handle and the means for indexing the position of therollers could. of course, be readily varied. Moreover the invention isnot limited to the construction of screw drivers and can be applied toother hand tools. The outer end of the shank could, for example, beadapted to receive spanner sockets. It is accordingly to be understoodthat the invention is in no way limited to the illustratedconstructional details and that many variations will fall within thescope of the appended claims.

I claim:

1. A rotary hand tool comprising an elongated tool shank with agenerally cylindrical coupling portion, a longitudinally extendingoperating handle assembly supporting the tool shank for rotation aboutthe axis of the cylindrical coupling portion and having a longitudinallyextending handle member and a coupling mechanism for selectivelycoupling the handle member to said coupling portion of the tool shankfor rotating the tool shank with the handle member the couplingmechanism comprising a plurality of rolling elements angularly spacedabout said generally cylindrical coupling portion of the tool shank andin rolling contact therewith, a longitudinally extending rigid casthousing mounted in the handle member having an axially extendinggenerally polygonal bore, a generally polygonal hard thin metal tubularliner of generally constant wall thickness throughout its extentconforming to and secured within the generally polygonal bore of thecast housing to define a generally polygonal chamber receiving thecoupling portion of the tool shank, the generally polygonal bore havinga generally polygonal cross-sectional configuration with a plurality ofat least as many rounded concave corners as the number of rollingelements and the generally polygonal tubular liner having acorresponding plurality of rounded concave corners defining angularlyspaced cavities about the coupling portion of the tool shank looselyreceiving individual rolling elements therein and angularly spaced hardmetal liner wedging surfaces for each rolling element extendinggenerally tangentially from the respective rounded corner on oppositesides of the respective rolling element for selective engagement withthe rolling element for wedging it against the generally cylindricalcoupling portion of the tool shank, and rolling elements positioningmeans comprising a collar surrounding the elongated tool shank coaxiallyof the cast housing and the tool shank and having an outer end portionat an outer end of the cast housing bore and a tubular portionprojecting from the outer end portion inwardly of the bore and theliner, said tubular portion being provided with detent means constantlyinterlocking the collar to the cast housing for rotating the collar withthe housing, said detent means providing alterna tive first and seconddetent positions, said collar in its first detent position holding eachrolling element relative to the respective liner wedging surfaces forrotating the tool shank with the handle member in a first angulardirection only, said collar in its second detent position holding eachrolling element relative to the respective liner wedging surfaces forrotating the tool shank with the handle member in the reverse angulardirection only.

2. The rotary hand tool of claim 1 wherein said thin metal liner engagesthe bore with a press fit connection.

housing bore has a generally cylindrical section surrounding saidtubular portion of the collar. and wherein the detent means interlocksthe generally cylindrical section of the cast housing and the tubularportion of the collar for holding the collar alternatively in its saidfirst and second angular positions relative to the handle

1. A rotary hand tool comprising an elongated tool shank with a generally cylindrical coupling portion, a longitudinally extending operating handle assembly supporting the tool shank for rotation about the axis of the cylindrical coupling portion and having a longitudinally extending handle member and a coupling mechanism for selectively coupling the handle member to said coupling portion of the tool shank for rotating the tool shank with the handle member, the coupling mechanism comprising a plurality of rolling elements angularly spaced about said generally cylindrical coupling portion of the tool shank and in rolling contact therewith, a longitudinally extending rigid cast housing mounted in the handle member having an axially extending generally polygonal bore, a generally polygonal hard thin metal tubular liner of generally constant wall thickness throughout its extent conforming to and secured within the generally polygonal bore of the cast housing to define a generally polygonal chamber receiving the coupling portion of the tool shank, the generally polygonal bore having a generally polygonal cross-sectional configuration with a plurality of at least as many rounded concave corners as the number of rolling elements and the generally polygonal tubular liner having a corresponding plurality of rounded concave corners defining angularly spaced cavities about the coupling portion of the tool shank loosely receiving individual rolling elements therein and angularly spaced hard metal liner wedging surfaces for each rolling element extending generally tangentially from the respective rounded corner on opposite sides of the respective rolling element for selective engagement with the rolling element for wedging it against the generally cylindrical coupling portion of the tool shank, and rolling elements positioning means comprising a collar surrounding the elongated tool shank coaxially of the cast housing and the tool shank and having an outer end portion at an outer end of the cast housing bore and a tubular portion projecting from the outer end portion inwardly of the bore and the liner, said tubular portion being provided with detent means constantly interlocking the collar to the cast housing for rotating the collar with the housing, said detent means providing alternative first and second detent positions, said collar in its first detent position holding each rolling element relative to the respective liner wedging surfaces for rotating the tool shank with the handle member in a first angular direction only, said collar in its second detent position holding each rolling element relative to the respective liner wedging surfaces for rotating the tool shank with the handle member in the reverse angular direction only.
 2. The rotary hand tool of claim 1 wherein said thin metal liner engages thE bore with a press fit connection.
 3. The rotary hand tool of claim 1 wherein the collar comprises a rolling element positioning portion holding the rolling elements in circumferentially spaced relationship about the coupling portion of the tool shank in surface confronting relationship with alternative wedging surfaces of the thin metal liner respectively, each rolling element being held against the respective alternative angularly spaced wedging surfaces of the liner with the positioning member in its two alternative angular positions respectively.
 4. The rotary hand tool of claim 3 wherein the cast housing bore has a generally cylindrical section surrounding said tubular portion of the collar, and wherein the detent means interlocks the generally cylindrical section of the cast housing and the tubular portion of the collar for holding the collar alternatively in its said first and second angular positions relative to the handle member. 